Amazon.com on Monday announced an e-textbook program for its line of e-reader devices: Kindle Textbook Rentals. This will encompass tens of thousands of textbooks for the 2011 school year from leading publishers like John Wiley & Sons and Elsevier, the online retail giant said. Students can rent books for between 30 and 60 days and will be able to extend rental periods. The program will provide students savings of up to 80 percent of the textbooks' list prices, according to Amazon.